Research On Low Frequency Oscillation Of Three Interconnected Regional Power Grid

With the growing scale of the grid and the interconnection of regional powergrid，dynamic stability of the power system becomes more and more prominent. Inorder to analyze Mengxi-Shandong, Chuanyu-Henan new area oscillation mode afterthe grid interconnection,we build three-machine simulation system to simulate andanalyze the new regional oscillation mode and its influencing factors.we discover thelaws of the new regional oscillation mode from the simulation result to ensure thedynamic stability of the grid operation and achieve maximum utilization oftransmission lines.Based on the analysis of the three-machine simulation system simulation, Wedefines one end unit to the other end unit oscillation mode (ETE mode) and the centerunit to the end units oscillation mode (CTE mode) and hedge operating mode、progressive operating mode、diverge operating mode of the three-machine chainsystem. From simulate and mathematical analyzes the small interferencecharacteristics of static load model and dynamic load model, We can not simpleobtain the load model how to influence the power grid dynamic characteristic fromthe small interfering characteristic of load model. But we can conclude that theinfluence of the motor load on the ETE oscillation mode damping characteristics isthe same with the constant power load. Simulate and analyzes the influence of loadmodels on the ETE oscillation mode damping characteristics of multi-modes andmulti-scenes, we can conclude that the ETE oscillation mode damping characteristicsis not only related to the load models, but also related to excitation regulator, etc.Simulate and analyzes the influence of the contact line power flow on the ETEoscillation mode damping characteristics of multi-modes and multi-scenes, we canconclude that with the increase of the receiving end contact line power fiow, dampingcharacteristics of the ETE oscillation mode becomes better, and with the increase ofthe sending end contact line power fiow, damping characteristics of the ETEoscillation mode get worse.Based on the simulation of three-machine simulation system and practicalsystem, we can conclude the law of the influence of load models and the contact linepower flow on ETE oscillation mode damping characteristic, which is verymeaningful for the actual grid operation and the study on dynamic stability.